exploitation

What are the techniques for exploiting computers today?

I've just read "Hacking: The Art of Exploitation" and I'm interested in this subject. The thing is, this book seems irrelevant to hacking now that OSes have non-executable stacks, canary values on the stack, etc. So, how what methods are used now to exploit computers? Edit: Sorry, I wasn't clear. I was wondering about how hackers attac...